Continuous filament yarn having low and variable twist method of making same



CONTINUOUS FILAMENT YARN HAVING LOW AND VARIABLE TWIST METHOD OF MAKING SAME Filed May 7, 1965 Dec. 12, 1967 K. IWNICKI ET AL 3,357,655v

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Attorneys United States Patent 3,357,655 CONTINUOUS FILAMENT YARN HAVING LOW AND VARIABLE TWIST METHOD OF MAKING SAME Kurt Iwnicki,.Ponthir, and Derek J. Wood, Raglan, England, assignors to British Nylon Spinners Limited, Pontypool, Monmouthshire, England Filed May 7, 1965, Ser. No. 454,138 Claims priority, application Great Britain, May 15, 1964, 20,315/ 64 7 Claims. (Cl. 242159) ABSTRACT OF THE DISCLOSURE A draw-twister for e.g. nylon is operated in a manner to produce constant traveller speed, this being accomplished by progressively decreasing the speed of spindle speed throughout the building of the yarn package. In addition, the filaments of the yarn are interlaced by air jet means after drawing and before wind-up. The yarn in the resulting package has low uni-directional twist decreasing in value from inside to outside of the package and has a compensatory degree of inter-filament cohesion along its length independent of uni-directional twist and sufficient to impart to the yarn as a whole the handling properties of a similar yarn twisted to a twist of at least 0.15 turn per inch.

Disclosure The invention concerns improvements in or relating to continuous filament yarn having low and variable twist.

It has been the common practice in the textile industry in such processes as weaving and warp-knitting, to use yarns which have been twisted, to enable the yarns to be handled and processed as compact entities, without fear of their becoming dissociated into their constituent fibres or filaments and hence becoming snarled or weakened by fibre or filament breakage.

Sometimes the amount of twist imparted to the yarns has been quite considerable, for example from 7-30 turns per inch in multifilament yarns, and this twist insertion has been carried out by throwsters as a separate operation on the yarn as supplied by the producer. Lately, however, with the improved uniformity of the continuous filament yarns produced, and with increased knowledge as to the handling and processing of such yarns having only a low degree of twist, it has become common to use and process continuous filament yarns in the so-called flat state in which they are produced. A flat yarn is one possessing no more than the standard low degree of twist commonly inserted as an incident of its production by the yarn producer; and this twist may be only of between turn per inch and M2 turn per inch. This small amount of twist is sufficient to impart to the yarn an adequate degree of compactness and of manipulability for at least a large proportion of subsequent textile processes.

It has long been appreciated by continuous filament yarn producers that the insertion even of the low degree of twist mentioned above is a brake on the possibility of improving productivity. Various alternative methods to twist insertion have therefore been proposed and some of them have been practised. In place of the conventional ring spindle wind-up of, for instance, the nylon drawtwister such alternative methods contemplate the use of an ordinary cheese wind up employing some sort of reciprocating traverse mechanism, together with the imparting of inter-filament cohesion by one of various means. For instance, as described in British patent specification No. 401,652 such inter-filament cohesion, in place of twist,

may be obtained by causing the filaments lightly to adhere to one another by the application to the filaments of a solvent or softener therefor. Again, in British patent specification No. 708,009 the necessary cohesion is produced by the application of alternating twist by friction from the sides of a special traverse guide. Yet again, in British patent specification No. 924,089 the cohesion is produced by filament-interlacing in defined plural air vortices.

It is nevertheless the case that, owing to their increased cost compared with that of drawtwisters, draw-winders need to operate at very high wind-up speeds in order to show an improvement in productivity. Such operation is not always feasible either from the mechanical or the processing points of view. Hence, any improved productivity that can be achieved on a drawtwister is still of great importance to the continuous filament yarn producer.

The present invention is concerned with just such an improvement in productivity and with the yarn produced thereby.

The invention is derived, in part, from an appreciation of the part played by the ring traveller in ring spindle apparatus of the kind employed, for instance, as the Windup on a drawtwister on which nylon continuous filament yarns are drawn and twisted.

Apart from its twist inserting function, the ring traveller has the ability and function to match the drawing speed to the winding-on speed of the yarn on the drawtwist bobbin. It has now been appreciated that if the twist inserting function of the ring traveller is reduced to its secondary function, rather than its primary one, and the traveller is employed solely to match the drawing speed to the winding-on speed and to impart suificient tension to the yarn to pull it, or at least to assist to pull it, from the draw roll, then the rotational speed of the traveller can be greatly reduced from that normally required and a concomitant gain achieved in the windingon speed and consequently in drawtwister productivity.

The latter gain follows from the relationship between traveller speed, spindle speed and yarn speed, which is given by the equation when T=Travel1er speed, r.p.m. S=Spindle speed, r.p.m. V=Yarn velocity, feet/min. r=Package winding radius, feet.

In order to maintain the traveller speed constant at the practical minimum value, it is necessary to wind the yarn on to the drawtwister bobbin with a build each traverse stroke of which is at a constant package winding radius, such radius increasing progressively throughout the build, and, concomitantly, the spindle speed has to be reduced progressively as that radius increases.

It follows from the progressive reduction in spindle speed, together with the constant traveller speed and a constant drawing speed, that the amount of twist inserted during the entire build will itself vary proportionately.

3 treatment,.theneteffectof which twist and which added cohesion-inducing treatmentis the attainment in the yarn of the handling properties of a continuous filament yarn having, say, the standard producers A turn/inch of twist. Such a yarn according to the invention is useful both as a means to the end of increased productivity and in its own right. Twist in yarn is often only useful as an aid'to further processing such as weaving, rather than as an attribute to the fabric into which it is formed; and the very low degrees of twist to be found in yarn according to the invention are sensibly insignificant in fabric. On the other hand, the presence of even these low degrees of twist does mean that the other cohesion-inducing treatment can itself be a very light one, having no significant effect on the yarn as it is found in the fabric. Thus, the yarn, when formed into fabric, is a compact and yet full-bodied filamentary structure, for its size. Furthermore, if the yarn is simply required as the supply for further yarn processing, for instance by crimping or other forms of bulking, then the absence from it of any marked twist and any marked other inter-filament cohesion, for instance, filament interlacing, can usually be regarded as an advantage.

According to one aspect of the invention, therefore,-we' provide a compact multifilament, continuous filament yarn having a low unidirectional twist of less than A turn per inch variable along its length and having a compensatory degree of inter-filament cohesion along its length independent of uni-directional twist and sufiicient to impart to the yarn as a whole the handling properties of a similar multifilament, continuous filament'yarn twisted to a twist of substantially at least 0.15 turn per inch.

Preferably, such a yarn has at least substantially constant inter-filament cohesion prop erties,derived from the twist and the added cohesion along its length.

The test of inter-filament cohesion may be the hook drop test of specification No. 924,089; the knots per meter test of French specification No. 1,347,444; or the test in which the air pressure to give a given number of filament loops in the yarn, in a turbulencejet, is measured. Also, according to another aspect of the invention, we provide a yarn package having tapered end-portions and being built with each successive layer at a constant package winding radius greater than that of the preceding layer, the yarn in said package being a compact multifilament, continuous filament yarn having ,a low unidirectional twist decreasing in value from inside to outside of the package, and having a compensatorydegree of interfilament cohesion along its length independent of unidirectional twist and sufficient to impart to the yarn as a whole the handling properties of a similar multifilament, continuous filament yarn twisted :to a twist of substantially at least 0.15 turn per inch.

Preferably, again, the yarn in such package has atleast substantially constant inter-filament cohesion properties throughout the package.

Experimentation has shown that below 0.15 turn per inch twist, or its equivalent in total interfilament cohesion, a multifilament yarn is unlikely to be a satisfactory proposition for subsequent textile processing.

'The added inter-filament cohesion can be achieved by filament interlacing, for instance by passing the yarn on its passage from the draw-roll of a draw-twister axially through a twin-cone air jet; or by imparting rapidly alternating twist of a net value of zero; or, again, by employing a spinning finish on the yarn to be drawn and twisted which finish has a degree of 'tackiness sufficient to cause the filaments lightly to adhere together. Or it may be achieved by a combination of any or all of the above alternative methods.

When the inter-filament cohesion properties of the yarn are desired to be constant throughout its length, some compensation for the variability of the twist is required to be made to the superimposed inter-filamentcohes'ion treatment.

Such compensation can automatically be brought about by filament-interlacing compactingdevices of the air jet level drops,-and this progressive .increase in interlacing can be made exactly to compensate for the progressive decrease in twist by suitable programming of the reduction in spindle speed.

Also according to another aspect of the invention, we provide a process for producing a yarn or a yarn package, both as defined above, which process includes the steps of forwarding multifilament, continuous filament yarn from the periphery of a roll rotating at a constant speed, winding the yarninto a package by a ring spindle device in a package build having the length of traverse stroke progressively decreasing throughout the-build, the speed of rotation of-the spindle of said ring spindle device decreasing throughout the build in a manner such as to maintain constantthe-speed of rotationof the ring traveller at a minimum value consonant with its imparting sufficient tension to the yarn to pull it"from said roll.

An interfilament cohesion treatment may be imparted to the yarn prior to its being forwarded by the said roll, or afterwards; but preferably it is imparted to the yarn on its passage between said roll and said ring spindle device. Conveniently, as indicated above, it is imparted by a filament-interlacing air jet, so that as the balloon tension falls during the doff and the twist level drops, so the degree of interlacing increases, and the level of filament cohesion along the yarn can be maintained substantially constant if desired. The air jet can be of a kind such as the double-cone jet above referred, which has also a slight forwarding effect on the yarn, so that the-yarn is assisted to depart freely from the periphery of the roll, e.g. a draw-roll, whereby a lower tension in the ballooning yarn can be tolerated. Hence, lighter travellers than normal may be employed, and reduction in traveller back wear-thus achieved.

One embodiment of the above-defined process will now be described with reference to the accompanying drawings, in which FIGURE 1 is-a diagram of the items of apparatusused in the embodiment which comprises draw-twisting;

FIGURE 2 is --a diagram of a yarn package according to-the invention;

FIGURE 3 is a diagram of a portion of yarn according to the invention.

The apparatus illustrated diagrammatically in FIGURE 1 depicts a draw-twister for e.g. nylon yarn,'with means for programming thereduction inthe spindle speed during the building of'a so-called longto-short, half-cycle yarn package.

'Undrawn yarn Y is withdrawn over one end of supply package '1, through thread-guide 3, by the action of feed roll 5. The feed roll is surface-driven by drive roll 7; and the yarn makes a plurality of wraps around 'the periphery of feed roll 5, the wraps being kept apart by threading :the yarn throughthread-guide 9.

From the feedroll '5, the yarn is stretched by passing it with -a plurality of wraps around snubbing-pin 11 and drawing it :therefrom, :at a rate several times that of the peripheral speed ;of feed roll ,5, by ,draw roll 13. The yarn makes a plurality of wraps around :the periphery of draw roll 13, the wraps being kept apart by separator roll 15.

From the draw .roll 13, the yarn is taken to the windup, via filament-interlacing air jet 17. Compressed air is provided to the jet (by pipe means not shown in the drawing); and the tension on the yarn is such that although the filaments are separated from one another in the jet and interlaced, no loops are formed in them. The wind-up comprises the standard ring spindle, consisting of balloon guide 19, ring 21 and traveller 23, with take-up package 25 rotatably driven by spindle 26. The spindle is driven by belt 27 which is passed in driving engagement with wharl 29.

The driving end of belt 27 is a pulley 31 on a shaft 33 rotating within bearings in the diagrammatically depicted device 35 for programming spindle speed variation.

In one exemplary process carried out according to this embodiment of the invention, a ring of 5% inch diameter was used on a nylon drawtwister, at which diameter the practical minimum speed of the ring traveller was calculated to be 1000 rpm.

The winding-on speed of the yarn was constant at 6,600 feet/min. throughout the doff, the spindle speed being varied to decrease from 15,000 r.p.m. at the start of winding to 6,100 rpm. at the finish of winding.

The twist in a nylon multifilament continuous filament yarn so produced varied from 0.19 t.p.i. at the inside to 0.08 t.p.i. at the outside of the package.

The air jet interlacer 17 between the draw-roll 13 and the ring spindle wind-up compensatively increased the filament cohesion to a value which was substantially equivalent to turn per inch twist in a similar yarn that solely possessed that twist as the interfilament cohesion agency. Compensation was arranged to be substantially proportional to the twist decrease, by suitable programming of the spindle speed variation by device 35.

In FIGURE 2, the parallel layers 37 of yarn in the yarn package are shown very diagrammatically, starting with the longest traverse length nearest to the barrel of the container 39.

In FIGURE 3, again very diagrammatically, it can be seen how the filaments 41 of the yarn are interlaced with one another and have a helical configuration due to a low amount of twist. The filaments are shown in more open condition than will actually be the case.

In the above description of the invention, nylon multifilament, continuous filament yarns have been specified, as has a ring spindle twist-inserting wind-up. It is to be understood however, that the invention is not limited to any particular yarn material, nor to variable twist inserted by such ring spindle apparatus. For instance, all other multifilament synthetic and cellulosic continuous filament yarns are comprehended in the invention; and another example of twist-inserting wind-up device is the cap spinner.

What we claim is:

1. A yarn package having tapered end-portions and being built with each successive layer at a constant package winding radius greater than that of the preceding layer, the yarn in said package being a compact multifilament, continuous filament yarn having a low uni-directional twist decreasing in value from inside to outside of the package and having a compensatory degree of interfilament cohesion along its length independent of unidirectional twist and suflicient to impart to the yarn as a Whole the handling properties of a similar multifilament,

continuous filament yarn twisted to a twist of substantially at least 0.15 turn per inch.

2. A yarn package according to claim 1 in which the inter-filament cohesion consists in filament interlacing.

3. A yarn package according to claim 2 in which the filament interlacing compensates substantially exactly proportionately for the decrease in twist.

4. A process for winding a yarn package having tapered end-portions comprising the steps of (a) forwarding multifilament, continous filament yarn from the periphery of a roll rotating at a constant speed,

(b) winding the yarn into a package by a ring spindle device with a package build in which the traverse stroke decreases in length progressively throughout the build,

(c) decreasing the speed of rotation of the spindle of the ring spindle device according to a programme during the winding of the package to maintain constant the speed of rotation of the ring traveller of said device, and

(d) interlacing the filaments of said yarn by air jet means to compensate for the decrease in twist resulting from the decrease in the speed of rotation of the spindle during passage of the yarn from said roll to said device.

5. A process according to claim 4 in which said air jet means tensions said yarn between said roll and said means.

6. A process according to claim 4 in which said interlacing increases inversely proportionately with the decrease in twist resultant from said decrease in speed of rotation of the spindle of said device.

7. In the method of drawing, twisting and winding up multifilament, continuous filament yarn which comprises forwarding the yarn from a constant speed feed roll to a constant speed draw roll rotating at a greater peripheral speed than the feed roll to draw the yarn and winding the yarn into a package by a ring and spindle device with a package build in which the traverse stroke decreases progressively throughout the build, the improvement which comprises interlacing the filaments of the yarn by air jet means after passage from the draw roll and maintaining the traveller speed constant throughout the build, at a minimum value consonant with its imparting sufficient tension to the yarn to pull it from the draw roll, by progressively decreasing the spindle speed throughout the build, to thereby form a yarn package in which the yarn has low uni-directional twist decreasing in value from inside to outside of the package and has a compensatory degree of inter-filament cohesion along its length independent of uni-directional twist and sufficient to impart to the yarn as a whole the handling properties of a similar multifilament, continuous filament yarn twisted to a twist of substantially at least 0.15 turn per inch.

References Cited UNITED STATES PATENTS 3,083,523 4/1963 Dahlstrom et al 57-14O JOHN PETRAKES, Primary Examiner. 

1. A YARN PACKAGE HAVING TAPERED END-PORTIONS AND BEING BUILT WITH EACH SUCCESSIVE LAYER AT A CONSTANT PACKAGE WINDING RADIUS GREATER THAN THAT OF THE PRECEDING LAYER, THE YARN IN SAID PACKAGE BEING A COMPACT MULTIFILAMENT, CONTINUOUS FILAMENT YARN HAVING A LOW UNI-DIRECTIONAL TWIST DECREASING IN VALUE FROM INSIDE TO OUTSIDE OF THE PACKAGE AND HAVING A COMPENSATORY DEGREE OF INTERFILAMENT COHESION ALONG ITS LENGTH INDEPENDENT OF UNIDIRECTIONAL TWIST AND SUFFICIENT TO IMPART TO THE YARN AS A WHOLE THE HANDLING PROPERTIES OF A SIMILAR MULTIFILAMENT, CONTINUOUS FILAMENT YARN TWISTED TO A TWIST SUBSTANTIALLY AT LEAST 0.15 TURN PER YARN.
 4. A PROCESS FOR WINDING A YARN PACKAGE HAVING TAPERED END PORTIONS COMPRISING THE STEPS OF (A) FORWARDING MULTIFILAMENT, CONTINUOUS FILAMENT YARN FROM THE PERIPHERY OF A ROLL ROTATING AT A CONSTANT SPEED, (B) WINDING THE YARN INTO A PACKAGE BY A RING SPINDLE DEVICE WITH A PACKAGE BUILD IN WHICH THE TRANSVERSE STROKE DECREASES IN LENGTH PROGRESSIVELY THROUGHOUT THE BUILD, (C) DECREASING THE SPEED OF ROTATION OF THE SPINDLE OF THE RING SPINDLE DEVICE ACCORDING TO A PROGRAMME DURING THE WINDING OF THE PACKAGE TO MAINTAIN CONSTANT THE SPEED OF ROTATION OF THE RIND TRAVELLER OF SAID DEVICE, AND (D) INTERLACING THE FILAMENTS OF SAID YARN BY AIR JET MEANS TO COMPENSATE FOR THE DECREASE IN TWIST RESULTING FROM THE DECREASE IN THE SPEED OF ROTATION OF THE SPINDLE DURING PASSAGE OF THE YARN FROM SAID ROLL TO SAID DEVICE. 